Elementary cursor theme is a nice black cursor theme by Elementary OS team. These cursors are outlined by white borders and subtle shadows for improved visibility on all background colours.
On first look they do look similar to Gnome's DMZ Black cursors, however there are quite a few differences which you can notice in the image above.
To install elementary cursor theme on Ubuntu, run following commands:
sudo apt install git git clone https://github.com/snwh/elementary-cursors.git sudo cp -pr elementary-cursors/elementary/ /usr/share/icons/ sudo update-alternatives --install /usr/share/icons/default/index.theme x-cursor-theme /usr/share/icons/elementary/cursor.theme 13 sudo update-alternatives --set x-cursor-theme /usr/share/icons/elementary/cursor.theme
Log out and log back in for the changes to take effect.