How to put sprite-frame behind 3D object and UI object?

I am using Cocos Creator 3
In my scene I have cube background image and UI button.

What I like to do is put the background image as canvas image and display behind the cube and the button.

I add additional canvas and camera to the scene. Then add the background image to it.
But I can’t get the background image to go behind the cube and the Button.

Is it due to layering or priority issue?

Can someone provide some assistance on this?

Please find the project in this link.
https://drive.google.com/file/d/1jqOj5m4ZGTtOrkU6rxBKekHhvzxHtK0v/view?usp=sharing