If you mean you want a widget to control content dynamically from the admin panel, then you can use the Advanced Custom Fields plugin by Elliot Condon to create custom dynamic content and retrieve it every place all over the website. After installing the plugin, simply create fields in the plugin page and get the content in every HTML tag you want. Like this:
<?php the_field( 'Your Custom Field Name' ); ?>
You can see a real example and full documentation on the ACF website.