NOTE: The kernel binaries are marked as UNSTABLE (see the link url). You may not do this in a production machine, or you have to know what you’re going to do and know about how to restore if something goes wrong (or see the link at bottom).
Ensure you have the -update and -security repositories enabled.
sudo apt update (or sudo apt-get update)
Install the linux-image-generic metapackage to install the latest kernel that is packaged and tested for your release of Ubuntu. The metapackage will pull in several dependencies including the actual kernel packages themselves.
Using the metapackage will ensure you get upgrades as they become available.
Note that apt cannot remove kernels from other sources - you must clean up those yourself.
Best Answer
From the Ubuntu Handbook:
NOTE: The kernel binaries are marked as UNSTABLE (see the link url). You may not do this in a production machine, or you have to know what you’re going to do and know about how to restore if something goes wrong (or see the link at bottom).