Hi,
From http://www.juniper.net/documentation/en_US/junos15.1/topics/concept/bfd-distributed.html :
"To determine if a BFD peer is running distributed BFD, run the show bfd sessions extensive command and look for Remote is control-plane independent in the command output."
This might be different on vMX though.
You can also verify if BFD is running on the PFE or routing engine with show ppm command:
RE> show ppm transmissions detail protocol bfd
Distributed: TRUE v/s Distributed: FALSE
On pfe show ppm can be used for statistics display on the pfe:
show ppm statistics protocol bfd
Hope this helps.
Cheers,
Ashvin