I will suggest you to follow a detailed manual of hybrid MBR here - https://www.rodsbooks.com/gdisk/hybrid.html
But as an example you can have a look (i have not mentioned any details here.)
sudo gdisk /dev/sdd
[sudo] password for root:
GPT fdisk (gdisk) version 1.0.4
Partition table scan:
MBR: protective
BSD: not present
APM: not present
GPT: present
Found valid GPT with protective MBR; using GPT.
Command (? for help): r
Recovery/transformation command (? for help): p
Disk /dev/sdd: 15130624 sectors, 7.2 GiB
Model: Storage Media
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): 4A7748B4-58A5-4521-B555-CAC28D452779
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 15130590
Partitions will be aligned on 2048-sector boundaries
Total free space is 4029 sectors (2.0 MiB)
Number Start (sector) End (sector) Size Code Name
1 2048 411647 200.0 MiB 0700
2 411648 4605951 2.0 GiB AF00
3 4605952 7489535 1.4 GiB 8300
4 7489536 10332159 1.4 GiB 0700
5 10332160 12089343 858.0 MiB 8300
6 12089344 15128575 1.4 GiB 8300
Recovery/transformation command (? for help): h
WARNING! Hybrid MBRs are flaky and dangerous! If you decide not to use one,
just hit the Enter key at the below prompt and your MBR partition table will
be untouched.
Type from one to three GPT partition numbers, separated by spaces, to be
added to the hybrid MBR, in sequence: 1 3 4
Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): n
I selected no since i already had EFI GPT partition with bootloader.If you don't have that partition then you have select yes,something like this -
Creating entry for partition #1
Enter an MBR hex code (default AF): af
Set the bootable flag? (Y/N): n
A note from hybrid MBR
GPT fdisk can create the EFI GPT (0xEE) placeholder partition either
before or after the hybridized partitions in the MBR table. (Note that
this has nothing to do with the disk sectors this partition protects.)
Each placement has its advantages. Putting the 0xEE partition first in
the table works best with GRUB Legacy and GRUB 2, which treat the disk
as an MBR disk if the first slot in the MBR is not a 0xEE partition.
This first-position placement of 0xEE, however, can render Windows
unable to read subsequent partitions if the disk is a removable disk,
such as a USB flash drive. Overall, if the disk is a hard disk, I
recommend putting the 0xEE partition first; if it's a removable disk,
putting it later in the table may work better.
Creating entry for GPT partition #1 (MBR partition #1)
Enter an MBR hex code (default 07):
Set the bootable flag? (Y/N): y
Creating entry for GPT partition #3 (MBR partition #2)
Enter an MBR hex code (default 83):
Set the bootable flag? (Y/N): n
Creating entry for GPT partition #4 (MBR partition #3)
Enter an MBR hex code (default 07):
Set the bootable flag? (Y/N): n
Recovery/transformation command (? for help): o
Disk size is 15130624 sectors (7.2 GiB)
MBR disk identifier: 0x00000000
MBR partitions:
Number Boot Start Sector End Sector Status Code
1 * 2048 411647 primary 0x07
2 4605952 7489535 primary 0x83
3 7489536 10332159 primary 0x07
4 1 2047 primary 0xEE
Recovery/transformation command (? for help): w
Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!
Do you want to proceed? (Y/N): y
OK; writing new GUID partition table (GPT) to /dev/sdd.
The operation has completed successfully.