1<?php
2// define the woocommerce_ajax_add_order_item_meta callback
3function action_woocommerce_ajax_add_order_item_meta( $item_id, $item ) {
4 // make action magic happen here...
5};
6// add the action
7add_action( 'woocommerce_ajax_add_order_item_meta', 'action_woocommerce_ajax_add_order_item_meta', 10, 2 );