How to add custom fields to a WooCommerce product

In this post, I’m going to walk through the entire process of adding custom fields to a WooCommerce product. Custom fields (also called product addons) include text fields, select fields, checkboxes, and so on. They allow the user to enter additional, personalised information about a product. The post will cover creating and displaying the custom fields, adding the custom field data to the cart, and inserting the data in emails and orders. I will include code examples throughout the article. By the end you will have learned to build your own custom field plugin for WooCommerce. The plugin will:
Create a custom field in Product Data section of a WooCommerce product
Use the value saved in that field to display a text input field in the product single page
Save the user input in the custom field to cart meta data
Pass the value of the custom field to the order object
Custom fields without coding
We’ll go through the process from start to finish. However, if you are looking for a simpler way to add custom fields, then take a look at the Product Extras for WooCommerce plugin. It will allow you to add many types of field to your products, including text inputs, number inputs,
Source: https://managewp.org/articles/17514/how-to-add-custom-fields-to-a-woocommerce-product

source https://williechiu40.wordpress.com/2018/06/12/how-to-add-custom-fields-to-a-woocommerce-product/