libcapnp-dev software package provides Capn Proto C++ library (development files), you can install in your Ubuntu 14.04 LTS (Trusty Tahr) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install libcapnp-dev
libcapnp-dev is installed in your system.
Make ensure the libcapnp-dev package were installed using the commands given below,
$ sudo dpkg-query -l | grep libcapnp-dev *
You will get with libcapnp-dev package name, version, architecture and description in a table
| Distro | Ubuntu 14 04 lts trusty tahr |
| Section | Library development |
| Package | libcapnp-dev |
| Version | 0.4.0-1ubuntu2 |
| Description | Capn Proto C++ library (development files) |
| Sub Section | libdevel |