I don't think there are any major calendar apps (Omnifocus 2, Calendars5, Fantastical 2, Pocket Informant, WeekCalendar, miCal, Moleskine Timepage, Cal, Wave Calendar, UpTo Calendar) that support the Apple Pencil I think which is very unfortunately if you have an Apple Pencil. It would be a good thing to suggest this feature to the developers.
I'm a big fan of Week Calendar and also miCal and Moleskine Timepage are nice calendars because of their support for travel time (see also
this post).
I did found this calendar app called '
Draw Calendar' though which probably supports it.