There are a few ways to do this.
The simplest is to make your object a child node of the active camera node.
The next simplest is to set up a camera that renders the object to a render target, and the paste the render target texture in the corner.
The third way would be to use “custom depth stencil” render pass shenanigans. Most of the tutorials for this is on “how to render object outlines,” but it can be used for a bunch of other effects, too (including compass roses and other such overlays.)