Two options you might want to consider

1. Export/Import
The easist way I dealt with this sort of stuff is to save the choice to a
spreadsheet once its selected.
I generally have a worksheet that contains all the choices and the option a
user selects.
This way I always have a hard copy of the choices a user selects for later
reference.

Then simply import the data back in to use.

2. Make a function to pass variables

Alternatively you could just make the other sub a function and run it that
way

Sub Dummy
Dim Option as String
Dim result as string
Dim i as intiger

Option = listbox1.value
i = 10
result = Values(Option, i)

End Sub

Function Values(Option As String, i As Integer)
....
Values = ...
End Function

Hope this helps