How to Install and Configure PHP 7.0 or PHP 7.1 on Ubuntu 16.04
sudo apt-get install -y apache2
sudo apt-get install -y php7.0 libapache2-mod-php7.0 php7.0-cli php7.0-common php7.0-mbstring php7.0-gd php7.0-intl php7.0-xml php7.0-mysql php7.0-mcrypt php7.0-zip
php -v
sudo vi /etc/php/7.0/apache2/php.ini
sudo systemctl restart apache2.service
Fonte: https://www.vultr.com/docs/how-to-install-and-configure-php-70-or-php-71-on-ubuntu-16-04