Hook for Node Add Field?
By the way, all the hooks are listed here there doesn't appear one that fits the task tho.

You can always add a custom validation to the field add form. 

/*
 * Implements hook_form_FORM_ID_alter()
 */
function mymodule_form_field_ui_field_storage_add_form_alter(&amp;$form, \Drupal\Core\Form\FormStateInterface $form_state) {
  $form['#validate'][] = 'mymodule_custom_add_field_validation';
}

/*
 * Custom Validate Callback
 */
function mymodule_custom_add_field_validation(&amp;$form, \Drupal\Core\Form\FormStateInterface $form_state) {
  // the code that performs the check
  // if (......) {
  //   $form_state-&gt;setErrorByName('label',
  //     t('This field already exists in another entity'));
  // }
}