Dropzone div with jquery validation plugin

Question

I want to check if user upload image with dropzone js and jquery vaalidation plugin.

Dropzone div:

<div class="photoimageUpload dropzone" id="photoimageUpload" role="form" method="post" action="PHP/photo_upload/photo_imageUploader.php" enctype="multipart/form-data"></div>

$("#photo_form").validate({
  rules: {
    photoimageUpload: {
      required: true
    }, 
    // ...

That div is inside one form with submit button:

<input type="submit" value="Confirm" class="btn btn-outline-secondary hvr-underline-from-center" name="btn" id="btn">