Has anybody on Quora ever found a hidden camera or voice recorder using the magnetometer on their smart phone?

What smartphone has a magnetometer?
And even if one did, I am not sure that a magnetometer would even detect such devices. A magnetometer is designed to detect ferrous metals and magnetic fields.
Tiny, hidden CCTV cameras and microphones are unlikely to even contain those items.
Using your smart phone to detect surveillance is pretty dumb - unreliable and unprofessional.
You want to get your hands on a professional Linear Junction Detector to do this...

Why do our parents love us?

This is natural. Every living being strives hard to preserve existence of his body, whether it is an ant, elephant or human. Nobody wants to die. That is to say every living being loves existence. The soul जीव however knows that however he loves this body, adore this body,

Where is the best safest place to live for $1200 month in the US?

You can live anywhere you want to live, but will have to be creative if you don't want to work or take part in you're community. Have you ever looked at all of the camper vans and motor homes in the 24hourFitness parking lot?