On Sunday, August 9, 2020 at 10:07:01 AM UTC-4, wrote:
Please is there any gadget/circuit/App that can detect a mobile phone when ;
1. even when the phone is off but the battery is inside.
2. When the phone is on
3. when the battery has been removed
thank you.

I saw something like that at the start of a 1983 season #2 episode #3 titled: "Red Hot Steel" from the 1980s Remington Steele drama series starring Stephanie Zimbalist. Pretty scary.