Debian unable to install php5.6-memcache?

Question

linux

Good afternoon, I can not install php5.6-memcache on debian

:~$ sudo apt-get install php5.6-memcache
Reading package lists... Done
Building dependency tree
Reading status information... Done
E: Unable to find package php5.6-memcache
E: Couldn't find any packages using pattern "php5 .6-memcache"
E: Could not find any package using regular expression "php5.6-memcache"

And on php7 it was put normally.
I don’t understand what it is in linux repositories, I just poked boom commands from the Internet, nothing helps.
Two questions:
1. Maybe there is a good lesson on Linux that you can watch and not when there will be no problems installing software on Linux. (what are repositories where to get them how to connect)?
2. And most importantly, how can I install this memcache module on the fifth version of php now?
Thank you!

Answer 1

Obviously, because there is no such package, at least in the official repositories:
https://packages.debian.org/search?lang=en&search...

Answer 2

https://deb.sury.org/
php repository for debian