How do I see which campaign someone came from when filling out a form?

With a hidden field. It reads a value from the address, e.g. ?utm_source=google, and the person doesn't see it. Under “Analytics” → “Sources”, Peak counts by utm_source anyway, otherwise by referring page, otherwise “Direct”.

1. 01In the builder, add the “Hidden field” block.
2. 02On the right under “URL parameter”, enter the name, e.g. utm_campaign.
3. 03Share the form link with the parameter, e.g. …?utm_campaign=fall.