I'm looking for a hobby to take up after moving to the…

If you use a metal detector, locals will probably come over and ask if you're looking for lost gold, or pressure you about it. They tend to suspect any foreigner of coming to steal gold. I'm not joking. I was asked if I came to steal gold before too. It was a complete stranger, and it wasn't even a remote place, and I wasn't doing anything that would look like searching for something.

Being near a mining area is definitely a good spot

Try scuba diving. You'll be thankful

If you're going to use electronic hobby equipment in the Philippines, check the legal requirements. Something you can just buy in Western countries may have licensing rules in the Philippines.