In /etc/apache2/ports.conf, change the port as

Listen 8079

Then go to /etc/apache2/sites-enabled/000-default.conf

And change the first line as

<VirtualHost *: 8079>

Now restart

sudo service apache2 restart

Apache will now listen on port 8079 and redirect to /var/www/html

Source: apache2 – Configure apache to listen on port other than 80 – Stack Overflow