app/views/yandex_captcha/_captcha.html.erb
<% if noscript %>
<noscript>
<% end %>
<div id="captcha_widget">
<% if error %>
<div id="captcha_error"><%= error %></div>
<% end %>
<div id="captcha_image">
<img src="<%= captcha[:url] %>" />
</div>
<input type="text" id="captcha_response_field" name="captcha_response_field" placeholder="Введите цифры" />
<input type="hidden" name="captcha_response_id" value="<%= captcha[:captcha] %>" />
</div>
<% if noscript %>
</noscript>
<% end %>