This Plugin allows widget drag n drop form with captcha to display in sidebars.You can also use shortcode to display form anywhere in the template or pages or post.

1. Upload plugin-name.php to the /wp-content/plugins/ directory
2. Activate the plugin through the 'Plugins' menu in WordPress
3. Go to "Email Subscribers" menu in the menu panel
4. Go to Appearance->Wdiget tab. drag "SIES subscription form" widget in the sidebar you want
5. use [sies_subc_form] shortcode to place the form anywhere you want in template

Subscription form in widget

Admin side listing of Subscribers