Have you considered using...Right click on List Box > Copy to Clipboard > Copy Possible Values and paste them in Excel? You can use this approach without using macros.
However, if you still need macros then you need something like this...
Sub GetPossibleValueFromLB
set LB = ActiveDocument.GetSheetObject("LB01")
boxvalues=LB.GetPossibleValues
for i = lbound(boxvalues) to ubound(boxvalues)
msgbox(boxvalues(i))
next
End Sub
Please integrate the above code with your original code.