Displaying Custom Input Value to Customer Order Details (My Account) page in Woocommerce

1. Adding the new custom field on the WooCommerce checkout page

You can add the new custom field in various places on the Checkout page. WooCommerce has defined many actions for the checkout page. Ideally, I would like my fields after the billing or shipping address fields.

We will add a custom field below the billing address fields. To add that field below billing address we will use action woocommerce_after_checkout_billing_form.

<?php
add_action( 'woocommerce_after_checkout_billing_form', 'display_extra_fields_after_billing_address' , 10, 1 );
function display_extra_fields_after_billing_address () {
    _e( "Delivery Date: ", "add_extra_fields");
    ?>
    <br>
    <input type="text" name="add_delivery_date" class="add_delivery_date" placeholder="Delivery Date">
  <?php 
}