Assuming you are on your virtual environment:
pip install ipykernel
python -m ipykernel install --user --name venvname --display-name "Python (venvname)"
# run `jupyter kernelspec uninstall venvname` to remove it afterwards
Assuming you are on your virtual environment:
pip install ipykernel
python -m ipykernel install --user --name venvname --display-name "Python (venvname)"
# run `jupyter kernelspec uninstall venvname` to remove it afterwards