If you have been constantly worried that you are been watched on camera, now this is for you: Hidden Camera Detector.
"The Camera Detector can quickly, easily, and discreetly conduct sweeps of your home, office, or hotel room to locate hidden wireless cameras. Simply point the compact camera towards walls and ceilings; and alarm will sound when a frequency of 50MHz to 3GHz is detected."
With the changing technology the surveillance cameras are becoming smaller & smaller & can be used in offices as well as in homes. So this can be of help to you.
Source: nerdapproved, Product page