Unable to install a kernel even though it compiled successfully

I'm trying to install a linux-Kernel version 4.9.228 in my ubuntu 20.04.The kernel compiled successfully, without any errors. I also executed the command :

sudo make modules_install install

When I rebooted my system, to check whether it made correct entry, I checked the files under the /boot/ directory:

• System.map-4.9.228
• vmlinuz-4.9.228
• initrd.img-4.9.228
• config-4.9.228

I don't know why but when I ran uname -r. It hasn't updated my version. It still says 5.4.0-37-generic.

Please guide me if I am missing something.

Note: The sole purpose of doing all this, is to learn how to add a system call and how to compile a kernel. I'm open to suggestions, if you got any. Thanks.