How to set up nginx+php7.0-fpm+memcached on Ubuntu 16.04?

Question

PHP

Ubuntu 16.04 runs nginx, php7.0-fpm, mariadb. On this stack a site on wordpress.
How to screw memcached or other good caching to reduce TTFB?
Memcached is installed, available on the port, but I can’t find a good article on how to tie it to nginx and how to force the backend to cache.