You can snap to double-click cells.
Open VBA, go to the worksheet that you want to connect to the event. Select "Worksheet" from the drop-down list in the upper left and "BeforeDoubleClick" in the upper right corner. Checking Target.Address is equal to the address of the cell you care about and call the function you need.
Something like that:
Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
If Target.Address(True, True, xlA1) = "$A$1" Then
Call MyDemo
End If
End Sub
Private Sub MyDemo()
MsgBox "Hello"
End Sub