Drawing over the model
If you want to use the model as a guideline to draw over, you’ll need to toggle the Layer tab. You can do so under Window>Layer. In the pop-up window, you can reduce the Opacity of the 3D layer by adjusting the lever on the top right-hand corner. Create a new layer over the 3D layer and use the Pen tool (or whichever drawing tool you prefer) to draw over the guide.
You can lock the 3D layer to prevent accidental changes. Reduce the Opacity enough to clearly see your drawing.