You can set a breakpoint in the function  by clicking in the left margin. It
appears as brown dot and the macro is supposed to stop when it gets there.
When this happens you can put  the mouse cursor on the name of any variable and
its value appears as a pop-up. You then step the through the macro with f8.

Rather than call the macro from the spreadsheet you can enter a command in the
immediate window (lower right in the editor) and it will start the macro.