Can I insert a pixel code on the form?

Is there a way to put a pixel on a form so i can retarget users?

FOr instance, most form builders have the ability to place a retargeting pixel in the header of the form.

How can I do this? 

If this "pixel" is a Javascript code then you can't add it on the form. We do not support script embedding into the forms for security reasons. However, you can add that pixel code on your webpage where the form is embedded.

You can also create a webpage and then make it as the Thank you page so that once the user completed the form, the user will be redirected to that page. Here's a guide: Redirecting-Users-to-a-Different-Page

Thank you.