ok, thanks
can you do this?

The FIDE laws of Chess are quite clear about this:
12.3a. During play the players are forbidden to make use of any notes, sources of information or advice, or analyse on another chessboard
So you cannot set up the position on your own board, that would violate this rule.

The FIDE laws of Chess are quite clear about this:
12.3a. During play the players are forbidden to make use of any notes, sources of information or advice, or analyse on another chessboard
So you cannot set up the position on your own board, that would violate this rule.
I am fairly sure that rule applies to FIDE sanctioned over-the-board play and does not apply to chess.com.
I think you can have a real board in front of you, but you can only move the pieces on the real board if a movement happens in the game, as analysing on the board and not in your head gives 1 player an advantage.
Even if it was allowed, I would recommend not to do it as visualization is a great skill to have.
This is right. You can't use the real board to try out lines you're thinking if playing. Treat it like a real tournament game,l. If you move a piece on the board, you have to move the same on the site. Better would be to move in the site and then mirror the move in the board.
But how will chess.com find out about it
they don’t have camera installed in our computer or something right?
or do they
I think you can have a real board in front of you, but you can only move the pieces on the real board if a movement happens in the game, as analysing on the board and not in your head gives 1 player an advantage.
Even if it was allowed, I would recommend not to do it as visualization is a great skill to have.
This is right. You can't use the real board to try out lines you're thinking if playing. Treat it like a real tournament game,l. If you move a piece on the board, you have to move the same on the site. Better would be to move in the site and then mirror the move in the board.