Check smoke detectors, clocks, plants near desks, anything that’s always been there and nobody questions.

To add to this as someone who has seen behind the curtain of how much of this tech is set up, lights are a common hiding place for cameras. Exit signs, parking lot lights, motion sensor lights, and the like. These are unfortunately also very difficult to detect by design, since they are expected to consume electricity, are almost always closed circuit with data wires parallel to the power wires, are practically impossible to observe in low light, and generate some heat even without any included surveillance equipment.