“wpcargo_after_package_details_script” hook is used to add customized script for the package details section.

add_action('wpcargo_after_package_details_script', 'wpcargo_after_package_details_script_custom_callback', 10, 1 );
function wpcargo_after_package_details_script_custom_callback( $shipment ){
	?>
	<script>
	  // You can add your custom script here.
	</script>
    <?php
}