Calderwood revealed to Voetbal International that Moyes' brother and agent, Kenny Moyes, asked him "eight months ago" to sound out Eredivisie clubs in the Champions League about interest in taking him on.
"As a coach, he is flexible, he belongs to the group of British coaches who can adapt to a different style. But for a German club, I think Moyes would fit well.
"In hindsight, it is nice that he is still going to be in the Champions League with Manchester United.
"But if Sir Alex (Ferguson) had stayed, I think he would have left Everton anyway."