Since version 1.10.0, arp-scan includes the ability to compile
it with capabilities support. Since the Debian kernel also
includes support for capabilities, this feature is also
included in this Debian package, although a normal user still
can't run all arp-scan options.

If you want to run arp-scan from a normal (non-privileged) user,
you have run the following as root:

# setcap cap_net_raw+p /usr/sbin/arp-scan

From there, all users can run all arp-scan options.