There are two commands needed for this to work:
systemctl is-active isc-dhcp-server.service
dhcp-lease-list --parsable
Cmnd_Alias SYSTEMD_STATUS_DHCPD=/usr/bin/systemctl is-active isc-dhcp-server.service Cmnd_Alias DHCP_LEASE_LIST=/usr/sbin/dhcp-lease-list --parsable www-data ALL= NOPASSWD: SYSTEMD_STATUS_DHCPD, DHCP_LEASE_LIST