According to the Ubuntu webpage Time Synchronisation with NTP:
> sudo apt install ntp
The manpage for `ntpd.conf` says
> wily (5) ntpd.conf.5.gz
> Provided by: openntpd_5.7p3_1_i386
and following that link: OpenBSD NTP daemon says
> This is an alternative implementation of the NTP software, made by the OpenBSD Project. It makes use of privilege separation, only implements a subset of the NTP protocol, adjusting the rate of the clock to synchronize the local clock.
> Alternative packages which provide similar functionality are **`ntp`** and **`chrony`**.
So according to the description, you could use any of those (at least there are packages for `ntp` and `crony`).