Step 1: Search for a plugin called “custom woocommerce checkout fields editor”
Step 2: Install and activate it
Step 3: Go to Woocommerce → Checkout & Register Form
Step 5: Fill the fields
Please note that the Name field can contain numbers, alphabets, and dashes but you can’t add spaces.
Type the title of your field in the label vacuum. Ex: Phone Number.
The placeholder text will appear at the background of the field and disappears when you start writing.
Step 6: Save changes
Congratulations you’ve done it!
Now this is how to add custom field in the billing and shipping address in woocommerce. if you have any question feel free to leave me a comment down bellow and i will be more than happy to help.