Baby monitor help

I’m looking for a monitor that connects to a phone and had its own handheld screen. Is this a thing? I’m not sure what/how to search for something like that.

I’m worried about family (or others) babysitting and giving them the log in to a phone only monitoring system for two reasons: I want it be simple for them and I worry they will stay logged in and look in on the baby without us knowing after they have gone home.

Does anyone else worry about this?

Thanks for your help!