prefill contact form 7 select with ultimate member plugin custom field

I would like to use the plugin “Ultimate member” in combination with CF7. I created a custom user meta field “dropzoneID” in ultimate member (UM) to store a simple string. I can already call the user field by UM function um_user(‘dropzoneID’); and echo it with PHP.

I have a CF7 form with a select “dropzoneID”, which I would like to have prefilled on page load with the “dropzoneID” from user meta data.

I’m very thankful for any suggestions to get it done.