These devices are called digitizing tablets. There are a lot of vendors of them. Several that come to mind are CalComp and Wacom.
Here is a digitizing tablet from CalComp like the one you describe:
http://www.gtcocalcomp.com/drawingboard6small.htm
Digitizing tablets are excellent tools, but they are pricey.
In this day, you can usually achieve equivalent accuracy much cheaper by using the camera in your cell phone and software. Look into photogrammetry software.
Wacom specialized in digitizing tablets that include tactile input for a 3rd dimension. Artists really love em, because its more like using a real paint brush or chisel.
D
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