Basically this is a rather specific case (having 3D objects over 2D background). While it was very often used in “early games” like Alone in the Dark, it’s rarely directly used nowadays. Usually if you create a 2D game you create everything in 2D, and if you have 3D elements, then you create everything in 3D as @michalis suggested earlier, by adding the background as a 3D quad and forcing the camera into a specific orientation.
As for examples simply using Lazarus you can check lazarus folder in examples. E.g. examples/lazarus/model_3d_viewer/ - you have a TCastleControl together with LCL compnents.
Note, that last unstable version of Castle Game Engine has a very decent Castle Editor, which enables creation of UI almost the same way as Lazarus does, but much more efficiently. However, at the moment it’s still a bit more complex, because you’ll have to load and the designed UI and assign some values (like events) manually. Thou it provides for much better flexibility, e.g. you can cross-compile such program to Android much easier.