1.
If you feel the objects are placed weirdly in the room, have an extra look at them and be vigilant.
2.
Most camera lenses, even the tiniest ones reflect light, so if there's a hidden camera it would reflect too. How do you check? Turn off the lights and switch on the flashlight in your smartphone to scan the room. If you spot a reflection then look for it and check for a hidden camera there.
3.
You can also search for an RF signal detector on Amazon and sweep the room with the bug detector.
4.
If you find a suspicious device in your room and you do not know what they are for, the best thing to do is to unplug the device and cover it with a towel.