Easiest way to create Kali Linux LiveUSB with persistence storage...

Your USB drive has a capacity of at least 8GB — the Kali Linux image takes over 3GB.

1. Download Kali Linux iso from here.

2. Use balenaEtcher to write the iso into your pendrive.

3. BalenaEtcher will create 2 partitions:

• iso9660 - 2.92 GB (your iso image)
• fat12 - 736 KB

4. Open KDE Partition Manager (GParted detected iso9660 as one partition as a whole) and create new partition (ext3 or ext4) on the third unused space and label it as persistence.

KDE Parition Manager

5. Create a mount point, mount the new partition there, and then create the configuration file to enable persistence. Finally, unmount the partition.

$ sudo mkdir -p /mnt/my_usb
$ sudo mount /dev/sdb3 /mnt/my_usb
$ sudo echo "/ union" > /mnt/my_usb/persistence.conf
$ sudo umount /dev/sdb3

How to test Live USB on VirtualBox Linux...

Plugged in your USB pendrive.

Check your USB drive details:

$ sudo fdisk -l

Add your user to disk group:

$ sudo usermod -a -G disk $USER

Open terminal and run the command below (replace X with your drive). There's no need for sudo:

$ vboxmanage internalcommands createrawvmdk -filename ~/usb.vmdk -rawdisk /dev/sdX

Next open VirtualBox and create new vm. When in the hard disk option, use an existing virtual hard disk file. Select usb.vmdk file that you've created earlier in the previous step.

Complete setup.

Now you can start the newly created vm to test your Live USB.