add an event procedure and hide the code

I have a vb macro that adds a workbook and adds code to
worksheet_selectionchange procedure. The problem is the code added
is available for everybody to see. I would like to hide the code
so no one can see it. Is it possible to do so?

I read somewhere that says even if the worksheet's VBProject is
programmatically protected, the protection only takes effect after
the sheet is saved. In other words, before the sheet is saved,
everyone can see the code. Not sure if this is true. I haven't
been successful in programmatically protecting a VBProject.