I didn't get how to install extensions using pecl to php5.6 or php7.0.

For example I have already installed version of libevent or amqp in php5.6.
Now when I type `pecl install libevent` and my active php version is php7.0 (using update-alternatives), pecl returns message that libevent already installed.
But it was installed only for php5.6 (when this version was active) and now I want to do it for php7.0.

Which commands could help me?