Use a Regular Expression.This finds only the first instance if there are multiples.
Option Explicit
Sub RegexMatch()
    Dim wb As Workbook, ws As Worksheet, cell As Range
    Dim lastRow As Long, r As Long, s As String
   ' build regex pattern
    Dim regex As Object, m As Object
    Set regex = CreateObject("vbscript.regexp")
    With regex
       .Global = False
       .MultiLine = False
       .IgnoreCase = True
       .Pattern = "([A-Z]{2}\d{9})" ' pattern AZ123456789
    End With
    ' data
    Set wb = ThisWorkbook
    Set ws = wb.Sheets("Sheet1")
    lastRow = ws.Cells(Rows.Count, "B").End(xlUp).Row
    For Each cell In ws.Range("B1").Resize(lastRow)
        s = cell.Value
        If regex.test(s) Then
            Set m = regex.Execute(s) '
            cell.Offset(0, 2) = m(0) ' matched term  in col D
        End If
    Next
    MsgBox lastRow & " rows parsed", vbInformation
End Sub