Unfortunately, you cannot run the CronJob inside a container of your application.
The only thing you can do is create a container which will contain your cronjob and necessary environment for running it and schedule to run that pod by a CronJob.
Here is an example of the configuration:
schedule: "*/1 * * * *" # syntax is a same as in system cron jobs
- name: hello
image: image_with_cronjob_code # here is an image with your cronjob
- date; echo Hello from the Kubernetes cluster