One more alternative:
Sub demo()
    Sheet1.ComboBox1.List = Range("A2:A11").Value
    SortTheBox Sheet1.ComboBox1
    
    Sheet1.ListBox1.List = Range("B2:B11").Value
    SortTheBox Sheet1.ListBox1
End Sub

Function SortTheBox(vCtl As Variant) As Boolean
    Dim i         As Long
    Dim j         As Long

    If Not IsObject(vCtl) Then Exit Function

    Select Case TypeName(vCtl)
        Case "ComboBox", "ListBox"
            With vCtl
                For i = 1 To .ListCount - 1
                    For j = 0 To i - 1
                        If .List(i) < .List(j) Then
                            .AddItem .List(i), j
                            .RemoveItem i + 1
                            Exit For
                        End If
                    Next j
                Next i
            End With

            SortTheBox = True
    End Select
End Function