How to make a custom field not visible but not "hidden"?

To my surprise, setting a Custom Field to be “Hidden” does not just mean it is not visible to the user, it seems it is not visible to client-side JavaScript either!

I may be wrong, but I was unable to find the value of my hidden field looking for a long time through its tags and attributes with Google Chrome Dev Tools.

Is there a way to hide a field from the user but still use it’s data on the client-side?