Django migration error ModuleNotFoundError: No module named 'captcha'

Encounter problems

The IDE is Pycharm, the captcha package has been installed, and 'captcha' is registered in the app list in the settings, and then migrated in the Terminal:

python manage.py migrate

The result is an error:

ModuleNotFoundError: No module named 'captcha'

Solution

Activate the virtual environment in Anaconda, cd to the manage.py path, and then migrate successfully

Operations to perform:
  Apply all migrations: admin, auth, captcha, contenttypes, login, sessions
Running migrations:
  Applying captcha.0001_initial... OK
  Applying captcha.0002_alter_captchastore_id... OK

Can someone please explain the reason of this problem...