This Displays MAC Address, add 1 textbox call it MacLocalIPAddressBox and one label called MACAddressDisplayLabel. Then all you need to do is add the code below 
and add local machines ip addresss ie 192.168.1.1 then press the button and the label will display the mac address for each local machines ip.

Declarations:

Declare Function SendARP Lib "iphlpapi.dll" Alias "SendARP" (ByVal DestIP As Int32, ByVal SrcIP As Int32, ByVal pMacAddr() As Byte, ByRef PhyAddrLen As Int32) As Int32


Code:

Public Shared Function GetMac(ByVal ipAddr As String) As String

        Dim macAddress As String = String.Empty
        Try
            Dim destIP As Net.IPAddress = Net.IPAddress.Parse(ipAddr)
            Dim IP() As Byte = destIP.GetAddressBytes()
            Dim IPInt As Int32 = BitConverter.ToInt32(IP, 0)
            Dim mac() As Byte = New Byte(5) {}
            SendARP(IPInt, 0, mac, mac.Length)
            macAddress = BitConverter.ToString(mac, 0, mac.Length)
        Catch ex As Exception
            Debug.Write(ex.Message)
        End Try
        Return macAddress

End Function

Private Sub button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles button1.Click

Me.MACAddressDisplayLabel.Text = GetMac(Me.MacLocalIPAddressBox.Text)
End Sub
