Connect the ESP32 board to the PC using the USB cable. The WROOM-32U should be recognized as a CP210x: CP210x USB to UART Bridge.
To check the device name for the serial port of your ESP32 board (or external converter dongle), run this command two times, first with the board / dongle unplugged, then with plugged in. The port which appears the second time is the one you need:
ls /dev/tty*
The currently logged user should have read and write access the serial port over USB. On most Linux distributions, this is done by adding the user to dialout group with the following command:
sudo usermod -a -G dialout $USER
Connect to the ESP with the miniterm that is part of the ESP-IDF installation:
~/development/esp32/idf-tools/python_env/idf4.2_py3.7_env/bin/miniterm.py /dev/ttyUSB0 115200