To add facebook pixel to your form, you need to add the facebook pixel code which you can generate from your Facebook pixel like the one on screenshot below, see this link for guide on how to generate the codes https://www.facebook.com/business/help/1021909254506499 details.
Here's how you can add the code to the form.
- Mouse over your form and click "Options", and then "Edit". See Screenshot
- On the "Form Settings", click the "Edit" button under "Header/Footer" .
4. If you'd like to monitor events/actions like "Complete Registration" every time a user submits your form, you can place the event tracking code in the Confirmation message/page. To do so while still editing your form go to Form Settings tab > Confirmation Options > Success Message > Edit Message. Follow step 3 above for instructions on how to place the code (you'll want to put it a line under your confirmation/thanks message)
5. Save your form.
You have multiple ways to test that the pixel code and event tracking is working: (a) go to https://www.facebook.com/analytics/(must be logged in) and select the Pixel analytics entity you created with the steps above (takes time to update); (b) follow section 4 here https://www.facebook.com/business/help/952192354843755