Is there a magnetic field around the phone in the middle of the night? Is it a ghost?

There is a magnetic field, not a ghost

There is a magnetic field around the mobile phone in the middle of the night, and the nearby signal tower will form a magnetic field to interfere with the use of the mobile phone. Surrounding household appliances will also have an impact on mobile phones, such as induction cookers and microwave ovens. It's not a ghost.

Magnetic field refers to the field that transfers magnetic force between objects. There is a magnetic field around the magnet, which cannot be seen or touched under the existing conditions.