(https://www.citrix.com/blogs/2016/04/07/using-the-crtl-key-with-citrix-receiver-for-linux/)[source]
On Ubuntu, you will need to use the dconf editor or gsettings to change the value:
gsettings set org.gnome.settings-daemon.peripherals.mouse locate-pointer false
OR
Install dconf editor: apt-get install dconf-editor
Launch dconf editor. Click on the Unity button and type “dconf” then click on the dconf editor icon.
Browse to org.gnome.settings-daemon.peripherals.mouse. “locate-pointer” key and make sure the checkbox is not checked to disable