Hi, the simplest way is to use VMware Converter. Just install it to your computer, select source VM and use "VMware Workstation" as destination.
More details here: VMware Knowledge Base
The reason why you need to use a converter is that Workstation uses a different virtual disk format than ESXi.
If you want to do this periodically, eg. your production runs on vSphere and developers use Workstation, VMcom Backup can do this automatically. Set up regular backups for your vSphere environment and then add a Backup Copy job which will copy your latest backup to your Workstation computer. This way you'll always have the most recent workstation-compatible copy at hand.
Assuming that the ESXi version, and the Workstation Version are compatible (e.g. support the same virtual hardware versions), you can either download the VM's files from the ESXi host manually, and open the VM in VMware Workstation, or - if you have network access to the host - you can even connect VMware Workstation to the ESXi host, and use the Download option from within VMware Workstation.
Please note that you may need to adjust some settings to make the VM work (e.g. the network settings Portgroup -> Bridged/NAT/Host-Only).