Hello @shxsy,
There is currently no way of directly linking mesh data from a Substance model graph into a Substance compositing graph. To achieve your goal, the idea is to export the model then use Designer to bake maps using that model.
First, you need to export the output of the Substance model graph as an FBX or OBJ file. Click RMB on the graph item in the Explorer panel, then select the Export... option to export a 3D scene out of that graph.
Then, link the exported file to your package, click RMB on the linked 3D scene resource and select the Bake model information option. You may then bake any map you require and use that map in a Substance compositing graph.
I hope this is helpful!
Best regards.