I'm not sure if this is what you are asking for.
This will copy a formula from sheet1 into a cell on sheet2:
Sheets("Sheet1").Range("A3").Copy
Sheets("Sheet2").Range("A3").PasteSpecial
Another option:
Sheets("Sheet2").Range("A3").Formula =
Sheets("Sheet1").Range("A3").Formula
By using the command Sheets it doesn't matter who is active.
Remember, it's better to use variables than strings ("Sheet1", "Sheet2", "A3")
. It uses less memory and the macro runs faster.