Install the App
Press Command+Space and type Terminal and press enter/return key.
Run in Terminal app:
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null
and press enter/return key.
If the screen prompts you to enter a password, please enter your Mac's user password to continue. When you type the password, it won't be displayed on screen, but the system would accept it. So just type your password and press ENTER/RETURN key. Then wait for the command to finish.
Run:
brew install libev
Done! You can now use libev.