https://launchpad.net/~psi-plus/+archive/ubuntu/ppa/+packages
Adjust the /etc/apt/sources.list.d/psi-plus*.list file: add main/debug at the end:
deb http://ppa.launchpad.net/psi-plus/ppa/ubuntu xenial main main/debug
apt update
apt install psi-plus-dbgsym psi-plus-plugins-dbgsym