How can I add hidden fields in the Contentful form to capture utm parameter values?

How can I add hidden fields in the Contentful form to capture utm parameter values?

I want to record fields such as source,medium, term, content, campaign etc in the form so I can pass on that information to my CRM system Salesforce?

How can I do that?

Background:
My campaign has a URL with custom utm values that takes the potential lead to a contentful form. I need hidden areas in that form to record UTM parameters so that vital information can get transfered to my CRM system - Salesforce. It’s essential for my sales and marketing team to know exactly which campaign that lead came from - all that information is in the custom URL.

Please help