On iPhone, the other person needs to tap Allow to let you access their phone remotely. On Mac, ask the other person to click the button with a purple screen icon in the top-left corner of the ...

One of the benefits to buying into the Apple ecosystem is that you can use one device to control another. Here's how that works between you iPhone and iPad.

Also: How to remotely access and control someone else's iPhone (with their permission) However, a little digging into Apple's security documents sheds more light on the update.