$ sudo apt-get update
$ sudo apt-get install libgnutls26-dbg 

libgnutls26-dbg is installed in your system.

Make ensure the libgnutls26-dbg package were installed using the commands given below,

$ sudo dpkg-query -l | grep libgnutls26-dbg *

You will get with libgnutls26-dbg package name, version, architecture and description in a table

libgnutls26-dbg package basic information: