You can export your custom checkout fields using WooCommerce Customer / Order / Coupon Export (by SkyVerge) plugin. Please follow below steps to choose the fields which you want to export.
- Go to the CSV Export Fields section in the Advanced Settings page of Woocommerce Checkout Field Editor.
- Select the checkbox "Enable CSV Export support".
- Choose the fields which you want to export from the multi-select box "CSV export columns".
- Click on the Save changes button.
Steps to Export the Custom Fields using Customer/Order CSV Export plugin
- Go to Dashboard → WooCommerce → CSV Export.
- Click on the Export button below the page.
- A popup will appear which will automatically export the data into a CSV file.