Windowed Unity program. Getting Color from Desktop.

Is there any way I can get a pixel color from the desktop? I'm wanting to create a unity program that can run in windowed mode (for dual screen computers) it can be set to the side and the user can press a button in the unity-made program and then click on a pixel on the desktop and return that color value to the unity program.

Is this possible? I'm not having much luck with finding anything other than in-game screenshots.