Magnetic field scanner
The iPhone magnetometer measures magnetic field strength. Findy compares what it reads against a baseline you set yourself, so you can investigate whether one specific object contains more hardware than it appears to.
The magnetic field scanner is free. No subscription is required.
What it measures
Electronics containing motors, speakers, shielding or magnets distort the magnetic field around them. Sweeping the phone slowly across one object, and comparing against a baseline taken away from electronics and metal, can reveal that an object is not as empty as it looks.
Findy reports deviation from your baseline — not an absolute measurement, and not a classification of what caused it. The baseline matters: taken next to a radiator or a laptop, every subsequent reading is meaningless.
Magnetic readings are not proof of a camera or microphone. Countless ordinary objects trigger a deviation: speakers, motors, chargers, magnets, metal structures, appliances, magnetic phone cases, door frames, furniture fittings and the building's own wiring. Treat a reading as a prompt to look at something, never as a finding.
What it is for, and what it is not for
Use it for
Investigating one specific physical object you already have a reason to be curious about — a smoke detector that sits oddly, a decorative item facing the bed, a clock with no obvious purpose.
Do not use it for
Sweeping a room automatically. Walking a phone around a room produces a constant stream of deviations from ordinary building materials and fittings, and tells you nothing.
How to take a reading that means something
- Remove magnetic phone accessories, cases and stands. They dominate the reading.
- Establish a baseline well away from electronics, appliances and metal.
- Move slowly around the specific object you are inspecting.
- Repeat the measurement to check the reading is stable rather than a momentary spike.
- Compare several sides of the object rather than one face.
- Compare against a similar object elsewhere in the room, if there is one — two identical fittings should read alike.
- Inspect the object visually before concluding anything.
Reading a result
Within your baseline
No meaningful deviation at this position. This does not mean the object is empty — small or well-shielded electronics may not move the reading at all.
Deviation worth checking
The field near this object differs from your baseline. Something ferrous, magnetic or electronic is present. That describes a great many harmless things.
Findy will never tell you a magnetic reading has identified a camera or a microphone. The magnetometer cannot distinguish a hidden device from a speaker magnet, and claiming otherwise would send people to dismantle furniture over a bracket screw.
Related
The guided inspection checklist tells you which objects are worth measuring in the first place. The Bluetooth scanner is the other free tool. Read the full limitations.
Last reviewed 2026-07-23 · Written and reviewed by the Findy developer.