How to install kernel headers for custom kernel?

I am using Ubuntu 22.04. The default kernel is 5.15.0-56. However, because I have issue with my laptop keyboard (bug id #216158, I should patch the kernel. There are steps how I patch the kernel.

uname -r (to check current kernel version: 5.15.0-56)

apt source linux-image-unsigned-5.15.0-56
cd ./linux-5.15.0
patch -p1 < ../path/to/patchfile
make oldconfig
make -j 16
make modules_install
make install

The bug has been fixed, but I don't know why my kernel change to 5.15.64. Though I use 5.15.0 as source file and use old kernel config.

And when I tried to install VMWare Workstation. I prompted to the following window:

It caused by directory /usr/src/linux-headers-5.15.64 not found.

My question is:

1. Why the kernel version changed from 5.15.0-56 to 5.15.64 even I use version 5.15.0 as source kernel file?
2. How to generate directory /usr/src/linux-headers-5.15.64 ?

These are kernel installed on my machine.

$ dpkg --list | grep "linux-image" | grep "^ii"
ii  linux-image-5.15.0-25-generic              5.15.0-25.25                               amd64        Signed kernel image generic
ii  linux-image-5.15.0-56-generic              5.15.0-56.62                               amd64        Signed kernel image generic
ii  linux-image-generic-hwe-22.04              5.15.0.56.54                               amd64        Generic Linux kernel image

Solved The Problem

After @Terrance give me some explanation, I tried to rebuild the kernel using similar steps I mention earlier. However the different is on the kernel's source file. I use the following command.

apt source linux-source-5.15.0

However, There is no kernel header located on /usr/src, however I can run VMWare Workstation 17 properly.

I was able to fix the problem in a different way.

https://youtu.be/xOnrdMQd1vU

sudo apt-get update && sudo apt-get upgrade -y

sudo apt-get install gcc build-essentials -y

Download VMware Workstation 17 https://www.vmware.com/go/getworkstation-linux

cd Downloads && chmod u+x VMware* && sudo ./VMware*

Run these commands in your terminal

openssl req -new -x509 -newkey rsa:2048 -keyout VMWARE17.priv -outform DER -out VMWARE17.der -nodes -days 36500 -subj "/CN=VMWARE/"

sudo /usr/src/linux-headers-$(uname -r)/scripts/sign-file sha256 ./VMWARE17.priv ./VMWARE17.der $(modinfo -n vmmon)

sudo /usr/src/linux-headers-$(uname -r)/scripts/sign-file sha256 ./VMWARE17.priv ./VMWARE17.der $(modinfo -n vmnet)

tail $(modinfo -n vmmon) | grep "Module signature appended"

sudo mokutil --import VMWARE17.der

After you have finished all of the commands above, you need to reboot your machine and then Enroll MOK (your key) and then reboot again. When you log back in, you will be good to go!

mokutil --test-key VMWARE17.der