how to config rsync as deamon when a file change and not with cron

I have multiple folders that I rsync now with cron like in this example.

rsync -aqz source1/  user1@machine1:/some/destination1
rsync -aqz source2/  user2@machine2:/some/destination2
... and so on

Everything is running fine, but I have a lot of crontabs as root, and most of the time nothing changes, and I am just blocking processor.

I would like to start the rsync processes only when a file somewhere on source has changed.

So I have read the documentation of the rsync.conf file, but I did not understand how this works. My rsync.conf file right now looks like this :

lock file = /var/run/rsync.lock
log file = /var/log/rsyncd.log
pid file = /var/run/rsyncd.pid

&merge /etc/rsyncd.d
&include /etc/rsyncd.d

and the /etc/rsyncd.d folder is empty.

how do I need to write the config in order that the rsync runs as daemon and just syncs when a file has changed.