$ dpkg -i couchbase-release-1.0-6-amd64.deb

$ apt-get update

$ apt-get install libcouchbase-dev build-essential php-dev zlib1g-dev

$ pecl install couchbase

$ vi /etc/php/7.0/cli/php.ini

  extension=couchbase.so  // add

$ php7.0-fpm & nginx restart