Hi there,
Hooks are coded into the templates, so they don’t exist inside your post content.
You can use the the_content filter hook to insert stuff using PHP.
But if you want to add multiple items then i would recommend using the Ad Inserter Plugin:
https://wordpress.org/plugins/ad-inserter/
It has a lot of the fucntions built in for specifying the locations you need.
NOTE = its not just for ads, you can add a form shortcode or any other content.