Get source code pgAdmin4

 wget https://ftp.postgresql.org/pub/pgadmin/pgadmin4/v2.0/pip/pgadmin4-2.0-py2.py3-none-any.whl

Install pip3

 sudo apt install python3-pip

Install virtualenv

 sudo pip3 install virtualenv

Create virtualenv in dir ~/py3-venv-pgadmin

 virtualenv --system-site-packages --no-setuptools --python=python3.5 ~/py3-venv-pgadmin

Activate virtualenv

 cd ~/py3-venv-pgadmin/bin
 source activate

Check pip3

 which pip3
 ~/py3-venv-pgadmin/bin/pip3

Install pgAdmin4

 pip3 install pgadmin4-2.0-py2.py3-none-any.whl

For desktop deployment

 cd ~/py3-venv-pgadmin/lib/python3.5/site-packages/pgadmin4
 touch config_local.py
 nano config_local.py

write:

 import os
 SERVER_MODE = False
 DATA_DIR = os.path.realpath(os.path.expanduser(u'~/.pgadmin/'))
 LOG_FILE = os.path.join(DATA_DIR, 'pgadmin4.log')
 SQLITE_PATH = os.path.join(DATA_DIR, 'pgadmin4.db')
 SESSION_DB_PATH = os.path.join(DATA_DIR, 'sessions')
 STORAGE_DIR = os.path.join(DATA_DIR, 'storage')

run:

 python3 ~/py3-venv-pgadmin/lib/python3.5/site-packages/pgadmin4/setup.py

Run pgAdmin4

 python3 ~/py3-venv-pgadmin/lib/python3.5/site-packages/pgadmin4/pgAdmin4.py

Exit virtualenv

 deactivate

For run pgadmin4 create script ~/py3-venv-pgadmin/pgadmin4.sh

 #!/usr/bin/env bash
 cd ~/py3-venv-pgadmin/bin
 source activate
 python3 ~/py3-venv-pgadmin/lib/python3.5/site-packages/pgadmin4/pgAdmin4.py

Create alias for bash

 nano ~/.bashrc

write at the end of file:

 alias pgadmin4='~/py3-venv-pgadmin/pgadmin.sh'

reload bashrc

 source ~/.bashrc

now you can run pgadmin

 pgadmin4