This is a follow-up question of How do you draw text in DirectX 11?
In Direct3D-12, things got much more complex and since it's new I couldn't find any suitable libraries online.
I'm building a basic Direct3D12 FPS Test application, and I like to display the FPS data on screen with my rendered image.
The general answer to questions like this is "if you have to ask, then you probably should be using DirectX 11." DirectX 12 is a graphics expert API that provide immense control, and is not particularly concerned with ease-of-use for novices. See this thread for more thoughts in this vein.
With that out of the way, one option is to use device interop and Direct2D/DirectWrite. See Working with Direct3D 11, Direct3D 10 and Direct2D.
UPDATE: DirectX Tool Kit for DirectX 12 is now available. It includes a SpriteFont / SpriteBatch implementation that will draw text on Direct3D 12 render targets. See this tutorial.