Check for Featured Image and Display It With The Caption

First check for the existence of the image then display it in the content area:

In the template us this:

// check if the post has a Post Thumbnail assigned to it.
if ( has_post_thumbnail() ) {
	the_post_thumbnail();
}

This defaults to the Thumbnail size under Settings.

Size can be set by adding sizing parameters as follows:

the_post_thumbnail('thumbnail');
the_post_thumbnail('medium');   
the_post_thumbnail('large');   
the_post_thumbnail('full');

or a custom size as follows:

the_post_thumbnail( array(100,100) ); //which will resize the image to these dimensions
the_post_thumbnail( array(100,100,true) ); //which will crop the image

Full details of the_post_thumbnail() function here:

https://codex.wordpress.org/Post_Thumbnails

Add a caption to the image details and display it using the following:

echo get_post(get_post_thumbnail_id())->post_excerpt;