I had to do this recently to get my Windows 7 virtual machine to work in Ubuntu 20.04 run with an older kernel. What you have to do is export the vm from VirtualBox and save it as an ova image. You can then open it in VMware and save it in its native format. It's similar to do it the other way, from VMware to VirtualBox. Instructions are here (https://www.howtogeek.com/125640/how-to-convert-virtual-machines-between-virtualbox-and-vmware/).
When you create a VM guest using Virtualbox, you can use the .vmdk format for the disk which is VMware's native format. However, that's VM disk. Not sure if it's the same thing as an .ova image but the end result should be the same. But I'll admit I haven't tried it.