I do something like this...

In DBrix notebook:

dbutils.widgets.text("runDateYYYYMMDD", "")
runDate = dbutils.widgets.get("runDateYYYYMMDD")

In Data Factory:

Pipeline > Parameters tab > New Parameter:

Name: RunDate, Type:String, Default Value:

Data Bricks Notebook Activity > Settings tab > New Base Parameter:

Name=runDateYYYYMMDD, Value=pipeline().parameters.RunDate