将自定义元数据添加到Woocommerce 3中的管理订单编辑页面

When I send the order to an external delivery service (API), I get the answer: $delivery_order_id = '100678'. In this matter, these data are stored in metadata.

How to display this value in the admin panel Woocommerce?

This can be done using dedicated hooks like woocommerce_admin_order_data_after_order_details this way:

add_action( 'woocommerce_admin_order_data_after_order_details', 'admin_order_display_delivery_order_id', 60, 1 );
function admin_order_display_delivery_order_id( $order ){

    $delivery_order_id = get_post_meta( $order->get_id(), 'delivery_order_id', true );

    $delivery_id = ! empty( $delivery_order_id ) ? $delivery_order_id : '<span style="color:red">' .__('Not yet.') . '</span>';
    echo '<br clear="all"><p><strong>'.__('Delivery Order Id').':</strong> ' . $delivery_id . '</p>';
}

Code goes in function.php file of your active child theme (or active theme). Tested and works.

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As LoicTheAztec said you can put any meta anywhere you want: just take it from 'get_post_meta...' and send to any block using your output function in add_action with name like 'woocommerce_admin_order_data...'