$ sudo apt-get update
$ sudo apt-get install gir1.2-ecalendar-1.2 

gir1.2-ecalendar-1.2 is installed in your system.

Make ensure the gir1.2-ecalendar-1.2 package were installed using the commands given below,

$ sudo dpkg-query -l | grep gir1.2-ecalendar-1.2 *

You will get with gir1.2-ecalendar-1.2 package name, version, architecture and description in a table

gir1.2-ecalendar-1.2 package basic information: