In addition to the chart labeler that Deborah noted, you can also use this
macro if for some reason you don't want/need to install an add-in:
Sub AddLabels()
Dim RngLabels As Range
Dim Ser As Series
Dim i As Long
If TypeName(Selection) = "Series" Then
Set Ser = Selection
Set RngLabels = Application.InputBox(prompt:="Select the label
range:", Type:=8)
Ser.HasDataLabels = True
For i = 1 To Ser.Points.Count
Ser.Points(i).DataLabel.Text = RngLabels(i)
Next i
Else
MsgBox "Select a series in a chart."
End If
End Sub
Add the macro to a standard module. Select the chart and then run the
macro. In the dialog box, add the reference to the data source like
"Sheet1!A1:A5".