user_details.rb

<%= f.hidden_field :user_phone %>
<%= f.hidden_field :user_address %>

<div>
  <ul>
    <li>
      User Address: <%= f.text_field :user_address %>
    </li>
    <li>
      User Phone: <%= f.text_field :user_phone %>
    </li>
  </ul>
</div>