Hi I want to add an input field onto the order page where I can add a Serial Number once a customer has ordered a product.

I would like this to go under the Order details.

I know you can add notes but want this to be obvious on the order page.

I have tried the following:

    // run the action 
    do_action( 'woocommerce_admin_order_data_after_order_details', $wccm_before_checkout ); 

   // define the woocommerce_admin_order_data_after_order_details callback 
      function action_woocommerce_admin_order_data_after_order_details( $wccm_before_checkout ) { 


    <p class="form-field _serial_number_field ">
    <label for="_serial_number">Serial Number</label><input type="text" class="short" style="" name="_serial_number" id="_serial_number" value="" placeholder="Serial Number"> </p>
  <?php }; 

  // add the action 
  add_action( 'woocommerce_admin_order_data_after_order_details', 'action_woocommerce_admin_order_data_after_order_details', 10, 1 ); 

I’m missing the save part but can’t get my head around what I need to do – so that the value I enter is saved to the product meta?

Any help would be appreciated