How do I add make a label appear onMouseHover for each individual object?

For example, I have a set of blocks that each have different names. OnMouseHover I want the text label (that contains the unique name of the block) to appear on top of the object when the mouse is on the surface of the object and disappear when the mouse is outside. When navigate to another object and have another unique name appear on top of it.

How do I do that?

I prefer something written in C# but I can try and convert JS to C#.