Magento – Magento 2 : how to add custom grid using ui-component in admin Form Tab

For adding image field, you can try using plugin and always try to avoid overwrite whole class.

Vendor/Module/etc/adminhtml/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\User\Block\User\Edit\Tab\Main">
        <plugin name="sr_stackexchange_user_form" type="Vendor\Module\Plugin\Block\Adminhtml\User\Edit\Tab\Main" sortOrder="1"/>
    </type>
</config>

Vendor/Module/Plugin/Block/Adminhtml/User/Edit/Tab/Main.php

namespace Vendor\Module\Plugin\Block\Adminhtml\User\Edit\Tab;

class Main
{
    /**
     * Get form HTML
     *
     * @return string
     */
    public function aroundGetFormHtml(
        \Magento\User\Block\User\Edit\Tab\Main $subject,
        \Closure $proceed
    )
    {
        $form = $subject->getForm();
        if (is_object($form)) {
            $fieldset = $form->addFieldset('admin_user_image', ['legend' => __('User Image')]);
            $fieldset->addField(
                'user_image',
                'image',
                [
                    'name' => 'user_image',
                    'label' => __('Image'),
                    'id' => 'user_image',
                    'title' => __('Image'),
                    'required' => false,
                    'note' => 'Allow image type: jpg, jpeg, png'
                ]
            );

            $subject->setForm($form);
        }

        return $proceed();
    }
}

Clear cache.

Configure the container with XML

Just create a NameSpace/ModuleName/view/adminhtml/ui_component/product_form.xml file with this content:

<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">  
<fieldset name="my_fieldset" class="My\Module\Ui\Component\Form\Fieldset">
    <argument name="data" xsi:type="array">
        <item name="config" xsi:type="array">
            <item name="label" xsi:type="string" translate="true">More Product Links</item>
            <item name="sortOrder" xsi:type="number">1000</item>
        </item>
    </argument>
</fieldset>

Dynamically create fields with PHP

This is where we will write our custom logic to inject fields into this fieldset.

So here is the NameSpace\ModuleName\Ui\Component\Form\Fieldset PHP class which.

<?php  
 namespace My\Module\Ui\Component\Form;


 use Magento\Framework\View\Element\UiComponent\ContextInterface;  
 use Magento\Framework\View\Element\UiComponentInterface;  
 use Magento\Ui\Component\Form\FieldFactory;  
 use Magento\Ui\Component\Form\Fieldset as BaseFieldset;

 class Fieldset extends BaseFieldset  
 {
/**
 * @var FieldFactory
 */
private $fieldFactory;

public function __construct(
    ContextInterface $context,
    array $components = [],
    array $data = [],
    FieldFactory $fieldFactory)
{
    parent::__construct($context, $components, $data);
    $this->fieldFactory = $fieldFactory;
}

/**
 * Get components
 *
 * @return UiComponentInterface[]
 */
public function getChildComponents()
{
    $fields = [
        [
            'label' => __('Field Label From Code'),
            'value' => __('Field Value From Code'),
            'formElement' => 'input',
        ],
        [
            'label' => __('Another Field Label From Code'),
            'value' => __('Another Field Value From Code'),
            'formElement' => 'input',
        ],
        [
            'label' => __('Yet Another Field Label From Code'),
            'value' => __('Yet Another Field Value From Code'),
            'formElement' => 'input',
        ]
    ];

    foreach ($fields as $k => $fieldConfig) {
        $fieldInstance = $this->fieldFactory->create();
        $name = 'my_dynamic_field_' . $k;

        $fieldInstance->setData(
            [
                'config' => $fieldConfig,
                'name' => $name
            ]
        );

        $fieldInstance->prepare();
        $this->addComponent($name, $fieldInstance);
    }

    return parent::getChildComponents();
}
}

NOTE : In above logic i added simple field. so you need to add logic for add more field using Jquery or Javascript or any other logic. i have give a siple logic how to add dynamic UI component field.