The granularity of the cron is of 60 seconds, therefore, by "normal" routes it is not possible to accomplish what it wants, every 1 second.
One solution is to get around PHP itself.
An idea, which is even adopted by several frameworks such as Laravel, for example is, invoke cron every 1 minute (this time is variable, user defined).
cron would run the PHP script every minute.
Within the PHP script, an "infinite loop" is controlled with 1 second pauses.
So you'll get what you want.
If you want you can extend it, making cron run every 5 minutes. In this scheme the PHP script would run for 300 seconds, that is 300 iterations.
Of course, it is recommended that you have a second PHP script that will do the iterations in the background.