Routing VPN traffic through another VPN

What you are asking is call VPN Chaining or Double VPN or Doblehop VPN.

There are several ways of achieving it:

• Doublehop VPN
  May be offered by some VPN providers as a static option. When you connect to a specific VPN server, your connection is immediately linked to another VPN server.

• Configurable multihop VPN client
  This VPN cascading is another option provided by some VPN providers and allows configuration from within the VPN client.

• Router Setup + VPN Client
  Here you configure one VPN service on your router, then use a VPN client on the computer.

• Browser Extension + VPN Client
  If the VPN provider also has a secure browser proxy, you may connect to a VPN server through the client first and then to another one through the browser extension.

• Host Machine + Virtual Machine
  Here you connect to one VPN on the host computer, then connect to another on the virtual machine. This requires the VM to use NAT for going through the host, rather than Bridge that goes directly through the router.