hola fijate en este ejemplo
Option Explicit
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (pDst As Any, pSrc As Any, ByVal ByteLen As Long)
Private Sub Form_Load()
Dim B() As Byte
Dim S As String
Dim S2 As String
S = "Hola Mundo"
ReDim B(Len(S) - 1)
CopyMemory B(0), ByVal S, Len(S)
S2 = String(UBound(B) + 1, Chr(0))
CopyMemory ByVal S2, B(0), Len(S2)
Debug.Print S2
End Sub
Saludos.