etc/adminhtml/events.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="catalog_product_delete_after_done">
        <observer name="custom_delete_product" instance="Facebook\BusinessExtension\Observer\ProcessProductAfterDeleteEventObserver" />
    </event>
    <event name="catalog_product_save_after">
        <observer name="custom_save_product" instance="Facebook\BusinessExtension\Observer\ProcessProductAfterSaveEventObserver" />
    </event>
    <event name="catalog_category_save_after">
        <observer name="custom_save_category" instance="Facebook\BusinessExtension\Observer\ProcessCategoryAfterSaveEventObserver" />
    </event>
    <event name="catalog_category_delete_after">
        <observer name="custom_delete_category" instance="Facebook\BusinessExtension\Observer\ProcessCategoryAfterDeleteEventObserver" />
    </event>
</config>