Magento 2 – How to Find Out Which Block is Called

For Block use the below code in your module's 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">
    <preference for="Magento\Sales\Block\Adminhtml\Order\Create\Shipping\Method\Form" type="[VendorName]\[ModuleName]\Block\Adminhtml\Order\Create\Shipping\Method\Form"/>
</config>

For phtml override create a xml file with name sales_order_create_load_block_shipping_method.xml on your module's layout folder and set template for this "order.create.shipping.method.form" and use your template file location as per the requirement.

Please try to update below your script code :

<script type="text/javascript">
    require([
        "jquery"
    ], function($){
        $('#submit-button').on('click',function(){  
            $.ajax({
                url:"'" + <?php echo $block->getAjaxUrl(); ?> + "'",
                data: {form_key: window.FORM_KEY},
                type: 'POST'
                success: function(response){
                    console.log(response);
                }
            });
        });
    });
</script>

---> XYZ/Sales/Controller/Adminhtml/StoreLocation/Index.php

<?php

namespace XYZ\Sales\Controller\Adminhtml\StoreLocation;

use Magento\Backend\App\Action;

class Index extends Action
{
    protected $resultJsonFactory;
    public function __construct(Action\Context $context,\Magento\Framework\Controller\Result\JsonFactory $resultJsonFactory)
    {
        $this->resultJsonFactory = $resultJsonFactory;
        parent::__construct($context);
    }

    public function execute()
    {
       $response = $this->resultJsonFactory->create();
       $response->setData(['test' => 'hello']);
       return $response; 
    }
}

hope its work for you