Create or select a form
From your HubSpot Marketing Basic, Professional, or Enterprise account, navigate to Contacts > Forms and either open an existing form or create a new form.
Add the necessary fields to your form by clicking on a field in the Add form field sidebar menu and dragging it into the form.
Edit field optionsHover over the field you want to make changes to and click Edit.
Select 'Make this field hidden'
In the sidebar menu, select the checkbox to Make this field hidden.
Choose value to be passed
From your available options under Field options, choose the value which should be passed onto your contact's record upon submission.
Once selected, click Save in the upper right-hand corner.
Test your form
Click the Test tab at the top to preview what your form will look like before taking your changes live. If you're using progressive profiling on any of your fields (Marketing Professional and Enterprise only), then you can click Preview form behavior, you'll notice that while your hidden field displays in the Preview form behavior sidebar menu, it doen't show in your actual form that visitors see.