In D7, using profile2 module, you would load the entity_metadata_wrapper from user object then access profile fields as such: $userWrapper->profile_XXX->field_XXX
Given that Profile2 is replaced by Profile module in Drupal 8, what is the Drupal 8's equivalent of accessing profile module's fields from a user object?
$userWrapper->profile_XXX->entity->field_XXX->value
$user = \Drupal::entityTypeManager()->getStorage('user')->load(300); ksm($user->profile_teacher); // NULL. ksm($user->toArray()); // Nothing related to teacher.