PHP 7.0 reached end of life on 03 Dec 2018 and is no longer being updated. It's strongly recommended to upgrade to the latest version as soon as possible. You can read the official PHP migration guide here.
sudo apt update
sudo add-apt-repository ppa:ondrej/php
sudo apt update
sudo apt install php7.0
php -v
echo '<?php phpinfo(); ?>' | sudo tee /var/www/html/info.php
http://your_server_ip/info.php