Do a physical search of your room
This involves a slow, meticulous sweep of the room or a building you suspect is wired. Look around for anything that seems different or out of place, such as flower arrangements, pictures on the wall or in unusual areas of your hotel room.
Turn off the lights and look around for tiny red or green LED lights
Some microphones or cameras have power on indicator lights, and if the person who sets it up is careless they may fail to cover or deactivate this feature. Also, when you turn off the light, you can carefully examine all mirrors in your room. These can be made transparent from one side so that a camera can see through.
Scan for webcams
Some cameras might be connected to the internet. Connect to the host’s Wi-Fi and use a free network scanner like Fing app to find internet-connected cameras.
Use an app
You can also download an app on your phone to detect a hidden camera. With these apps, you can move your phone around the suspected area, and if a strong field is detected, there is a good chance of a camera hidden within the wall. Examples of apps for detecting hidden camera are Hidden Camera Detector and Hidden Device Detector Cam Bug + Magnetometer.
Invest in a detector
If you are a frequent traveller and spend a lot of time in a hotel room, you may want to invest in a bug detector. There are professional camera detectors you can buy. For real peace of mind, it could be worth investing in.