Car insurance

I hope this is the right place… Delete if not!

Hey all, UK based

Insured with 1stCentral and I’ve got a Black Box.

I’ve got to register my phone with it and so does my partner as they’re a named driver.
However, if they’re a passenger and using their phone, will the black box pick it up and flag it?

Also it won’t effect me at all when he’s driving in his own car will it?
Just wondering if anyone has had an experience with this, thank you!