Sound frequency generator

[Rad-x]

Hello. I am new to all this and I am wanting to create a tool which is around the size of a torch or USB device and can generate sound tones at the press of a button. For example...

On the button being held down, it generates sound from a very low frequency to a very high one and then back again.

Please help. What would I need?

[Rad-x]

Please help. I am wanting to make a toy. Kind of like the Doctors sonic screwdriver in doctor who.