How to Add a Product Custom Field to Single Product Pages in WooCommerce

 If you're running a WooCommerce store and want to provide your customers with the ability to add personalized notes to their selected products, you can easily achieve this by adding a custom product note field. In this guide, we'll walk you through the steps to create a custom product note field on single product pages.

Step 1: Add Custom Product Note Field

Open your theme's functions.php file and add the following code to insert a custom product note field below the product meta on single product pages:

Step 2: Add a Hidden Field

Insert a hidden field in the add-to-cart form to store the product note. Add the following code:

Step 3: Capture Product Note in Cart Item Data

Capture and store the product note in the cart item data using the following filter:

With these steps, your WooCommerce store will now have a custom product note field on single product pages, allowing customers to add personalized notes to their selected products during the shopping process.

Ref- StackOverflow