Karrde

Includes a file’s contents in the widget. Quick and dirty, all this does is use the PHP include function to include the specified file in the widget. There is NO checking done whatsoever on the file, so use it at your own risk. I wrote this because I couldn’t find a widget to do this ? plugins exist for using include in posts and pages, but not in widgets.

Include Widget

Includes a file's contents in the widget.

gr8nilay

This plugin will include your created custom fields through Custom Field Suite plugin for Yoast SEO Analysis Calculation.
Read this first: 
This is only for pages not the custom post types or other default post types.

Boost Yoast Analysis CFS

This plugin will include your custom fields ( created with Custom Field Suite plugin ) for Yoast SEO Analysis Calculation

Include Widget vs Boost Yoast Analysis CFS