root@zbx:~# cat /etc/environment 
export PYTHONPATH=/usr/local/lib/python3

root@zbx:~# echo $PYTHONPATH
/usr/local/lib/python3

root@zbx:~# python -c "import sys; print(sys.path)"

['', '/usr/local/lib/python3', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages']

root@zbx:~# cat /etc/zabbix/zabbix_agentd.d/pythonpath.conf
UserParameter=displayPythonPath,python -c "import sys; print(sys.path)"

root@zbx:~# zabbix_get -s 127.0.0.1 -k displayPythonPath

['', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages']