So I asked the guy at the store for a finger mouse and he looked at me like I was crazy so I told him I want a mouse on my finger and he said there is no such thing.
I told my wife I am designing a finger mouse and then she came home with small flat keyboard that has a pad you slide your finger on.
There’s various types of mice that would do what you want
Here’s a presentation mouse, also
http://www.officemax.com/technology/keyboard-mouse-accessories/mice/product-prod2990132
And there’s also little tiny mice.