Precisely what you are attempting to achieve - and how you have "hooked up" your iPad and iPhone is unclear. If you can describe exactly what you have done, and how your devices are connected, contributors are more likely to be able to offer appropriate help or advice.
Perhaps this user-tip, authored by one of our senior contributors, will help you to describe the problem:
Writing an effective Apple Support Commun… - Apple Community
That aside, if your iPad or iPhone repeatedly chimes when connected to its Power Adapter, this often indicates that either the charging cable or Power Adapter has a fault, or the Power Adapter is not sufficiently powerful to reliable charge the connected device. Be aware that an iPad requires at least 12W (i.e. 2.4A @5V) to reliably charge. Some Power Adapters intended for iPhone can only output 5W, this being insufficient to charge an iPad.
As for your camera flash responding to events and notifications, there is an Accessibility setting that controls this behaviour:
Settings > Accessibility > [Hearing] Audio & Visual > LED Flash for Alerts - set as required
