Ubuntu Server Installing PHP 7 WITHOUT Apache

Use the command:

sudo apt install php7.2 php7.2-common php7.2-cli php7.2-fpm

It will require the php7.2 dependencies in strict mode (WITHOUT apache2).

If you just request php7.0, it'll install Apache as default. Do apt-get install php7.0-fpm and it'll install as FPM instead, leaving something like nginx up to you.