Try:
Sub Demo()
Application.ScreenUpdating = False
Dim StrFnd As String, i As Long
StrFnd = "0,1,2,3,4,5,6,7,8,9"
With ActiveDocument.Range.Find
.ClearFormatting
.Replacement.ClearFormatting
.Forward = True
.Wrap = wdFindContinue
.MatchCase = True
.MatchWholeWord = True
.MatchWildcards = False
.MatchSoundsLike = False
.MatchAllWordForms = False
For i = 0 To UBound(Split(StrFnd, ","))
.Text = Split(StrFnd, ",")(i)
.Replacement.Text = Chr(Asc(Split(StrFnd, ",")(i)) + 17)
.Execute Replace:=wdReplaceAll
Next
End With
Application.ScreenUpdating = True
End Sub