I have one.
..perhaps so has your daughter.
If she tried to get on my machine, I'd detect the logon.
The only way to prevent their use is to epoxy the keyboard into its socket or check for unknown gadgets everytime you use the computer (they're small, look like pc to usb adaptors).
IIRC you can get one on E-bay for about $15.
Your computer can be owned. Especially if you use windows (not trying to hijack the tread but it's true).