@Psubond yes, if you got scanned by pike you will get this message on the screen (somewhere down in the middle). But if she using her Scan, she will automatic spotted on the Mini map.
When you got scanned by Sentry it will make a Buzz (so it is possible you know that you got spotted)
All other Scans are silent like the proximity sensors, SOFLAM, the Drone and the close-range sensor of the vehicles.
But I think that most of the players are not aware that they get mini map spotted by shooting their gun.
@ElliotLH yes, she scans an area and when you in it you get this message.