Sub test()
    Dim WDDoc As Object
    Set WDDoc = ThisWorkbook.Sheets("Лист1").OLEObjects("Object 1").Object
    With WDDoc.Content
        .Find.ClearFormatting
        .Find.Replacement.ClearFormatting
        With .Find
            .Text = "Текст"
            .Replacement.Text = "Замена"
        End With
        .Find.Execute Replace:=2
    End With
    Set WDDoc = Nothing
End Sub

Dim WDDoc As Word.Document

Sub test()
    Dim OLEObj As OLEObject
    Dim ws As Worksheet
    Dim WDDoc As Object
    Application.ScreenUpdating = False

    Set ws = ThisWorkbook.Sheets("Лист1")
    Set OLEObj = ws.OLEObjects("Object 1")
    OLEObj.Activate 
    Set WDDoc = OLEObj.Object
    With WDDoc.Content
        .Find.ClearFormatting
        .Find.Replacement.ClearFormatting
        With .Find
            .Text = "Текст"
            .Replacement.Text = "Замена"
        End With
        .Find.Execute Replace:=2
    End With
    ws.Cells(1,1).Activate

    Application.ScreenUpdating = True
    Set OLEObj = Nothing
    Set ws = Nothing
    Set WDDoc = Nothing
End Sub

Sub Test()
    Dim XLObj As Excel.Workbook
    Set XLObj = ActivePresentation.Slides(1).Shapes("Table").OLEFormat.Object
    Dim i As Long
    With XLObj.Worksheets(1)
        For i = 1 To 10
            .Cells(i,1) = i
        Next i
    End With
    Set XLObj = Nothing
End Sub