the_post_thumbnail_caption( int|WP_Post $post = null )

Source

File: wp-includes/post-thumbnail-template.php

function the_post_thumbnail_caption( $post = null ) {
	/**
	 * Filters the displayed post thumbnail caption.
	 *
	 * @since 4.6.0
	 *
	 * @param string $caption Caption for the given attachment.
	 */
	echo apply_filters( 'the_post_thumbnail_caption', get_the_post_thumbnail_caption( $post ) );
}