Sub Demo()
'Routine is in code module of userform
Dim data() As String
Dim rng1 As Range
Dim rng2 As Range
Dim rw As Long
Dim cl As Range
'Define which ranges, best to use range names instead of regular cell addresses
Set rng1 = Range("NameForComboColumn0")
Set rng2 = Range("NameForComboColumn1")
ReDim data(1 To rng1.Rows.Count, 2) 'Set size of array. Assumes rng1 and rng2 have equal length!
'Load values range 1
For Each cl In rng1
rw = rw + 1
data(rw, 1) = cl.Value
Next
'Load values range 2
rw = 0
For Each cl In rng2
rw = rw + 1
data(rw, 2) = cl.Value
Next
'Fill listbox with data
Me.Listbox1.List = data
End Sub