Bhagirath Dhanani

Allow to display comment form inside post, page and widget.
Basically comment is inbuilt feature in WordPress but in some case we need embedded comment form.
Example.
* we need to embedded comment inside post.
* some theme build without comment form for pages or custom post type.
* you want to display comment form for specific post only, so you can disable comment for all page and use shortcode to display comment.
* in custom development you need comment form inside widget.
so here we have comment form shortcode to display comment using shortcode inside post,page or widget.
Comment Form Shortcode Help
You can use below ShortCode in post or page or in widget to show comment form.
[comment comment_file =”/comments.php”]
Here comment_file is optional, if you have custom comment file, you have to pass here.
How To Use : 
[comment]
[comment comment_file =”/short-comments.php”]

Comment Form Shortcode

Sirius Pro

This plugin allows you to display comments and comment form anywhere in WordPress. The comments list can be displayed for WordPress pages and posts without modifying the code and it works with most of the available themes. Just install and activate this plugin and use [sp_comments_block] shortcode anywhere in WordPress to display comments list and comment form.
Read more about this plugin on <a href="https://siriuspro.pl" rel="nofollow ugc">WordPress</a> blog.

Comments Shortcode

This plugin allows you to use a shortcode anywhere to display comments on WordPress pages and posts along with the comment form.

Comment Form Shortcode vs Comments Shortcode