How to set a Text on a GameObject?

Hey guys, I tried to get an answer by using google but couldnt find any successful solution for my problem. I habe a cube in a room and I want to display on this cube the temperature of the room (sth like a head indicator). My problem is ,that I cant set a text to the cube, I tried 1000 ways but yeah.... I even tried to do it with TextMesh and using a "3D Text Shader" but it looks like crap....

Does sb know how to display text on an Cube? I dont want to have the text on the camera/screen.