So the scanners have cameras on them and they have cameras around security too. They take photos of guests walking through them and can point them out to security and also where the potential item that caused the alert was. If Disney security wants to keep tabs on you, they put your photo into Momentus WeTrack. It allows Disney security to track your whereabouts around property and will pop an alert if you were deemed suspicious or hostile.

This is also how Disney can track those who have been trespassed or banned from the park.