Adding dynamic list-field to Woocommerce checkout

Hi,

I am trying to create a new field (select-list) to Woocommerce checkout-page so that when user inputs/changes the zipcode-field’s value, this new field fetches the available values.

I have already added the field but I’ve got no clue which action hook is the one that I should use when zipcode’s value is changed so that I could use that value to fetch the list-options (selected zipcode affects to the select’list’s rows)?

I’d appreciate any tips how to proceed with this.

https://www.ads-software.com/plugins/woocommerce/