Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
If Target.Column > 1 Or Target.Row < 4 Then Exit Sub
Dim i As Variant
Cancel = True
With Sheets("Feuil1") 'nom à adapter
i = Application.Match(Target, .Columns(1), 0)
If IsNumeric(i) Then Target(1, 2) = .Cells(i, 2).FormulaR1C1 Else Target(1, 2) = ""
End With
End Sub