Capture Cell Value on left mouse single click in Excel VBA

This code will check to see if multiple cells are selected at once then it checks to see if the cell is empty. If it is empty then it exits otherwise it stores the value is cell N1. You can change which cell the value gets stores at. If N1 has a value it goes to the next empty cell in column N.

Dim oval
Dim N As Long
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.Cells.Count < 2 Then
    If Target = Empty Then
      Exit Sub
    End If
oval = Target.Value
MsgBox "The value saved is " + oval + "."
If Range("N1").Value = "" Then
    N = 1
Else
    N = Cells(Rows.Count, "N").End(xlUp).Row + 1
End If
Cells(N, "N").Value = oval
End If
End Sub

If you would settle for a double mouse click, you could try something like

Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
    MsgBox Target.Value
    Cancel = True
End Sub

How about this? Just wrote it, it will not register a mouse click if you click where you could have reached with the keyboard

Enter Under Worksheet Code:

XXXXXXX
Option Explicit
Private prevTarget As Range
Private Sub Worksheet_Activate()
Set prevTarget = Selection
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)

    Dim wasMouseClick As Boolean
    Dim ch1, ch2, ch3, ch4, ch5, ch6, ch7, ch8, ch9 As String
    On Error Resume Next
    ch1 = prevTarget.Offset(1, 0).Address
    ch2 = prevTarget.Offset(-1, 0).Address
    ch3 = prevTarget.Offset(0, 1).Address
    ch4 = prevTarget.Offset(0, -1).Address
    ch5 = prevTarget.End(xlDown).Address
    ch6 = prevTarget.End(xlToLeft).Address
    ch7 = prevTarget.End(xlToRight).Address
    ch8 = prevTarget.End(xlUp).Address
    On Error GoTo error_noPreTarget

    If Not (Target.Address = ch1 Or _
       Target.Address = ch2 Or _
       Target.Address = ch3 Or _
       Target.Address = ch4 Or _
       Target.Address = ch5 Or _
       Target.Address = ch6 Or _
       Target.Address = ch7 Or _
       Target.Address = ch8) Then
        wasMouseClick = True
    End If
    Set prevTarget = ActiveCell
    If wasMouseClick Then
        Debug.Print wasMouseClick ' replace with what you want when wasMouseClick = True
    End If

Exit Sub
error_noPreTarget:
Set prevTarget = Selection
End Sub