@KimYujin Welcome to Q&A forum!
Before answering your questions would like to understand your scenario better so that we can assist you better in addressing all your questions and best practices for using Azure IoT Hub.
To get more context about Azure IoT Hub, please refer below.
IoT Hub is a managed service, hosted in the cloud, that acts as a central message hub for bi-directional communication between your IoT application and the devices it manages. You can use Azure IoT Hub to build IoT solutions with reliable and secure communications between millions of IoT devices and a cloud-hosted solution backend. You can connect virtually any device to IoT Hub.
IoT Hub supports communications both from the device to the cloud and from the cloud to the device. IoT Hub supports multiple messaging patterns such as device-to-cloud telemetry, file upload from devices, and request-reply methods to control your devices from the cloud. IoT Hub monitoring helps you maintain the health of your solution by tracking events such as device creation, device failures, and device connections.
IoT Hub's capabilities help you build scalable, full-featured IoT solutions such as managing industrial equipment used in manufacturing, tracking valuable assets in healthcare, and monitoring office building usage
we would like to know how the existing IoT device can be used with the Azure IoT Hub.
Could you please share more details about the IoT device? what type of device are you referring to? what exactly are you trying to achieve with this device?
Could we start and use the Azure IoT Hub without developers?
It completely depends on the scenario and usage. You can create an IoT Hub without any development experience. how ever, to communicate between the devices and perform other operations you should have basic level of programming understanding
I would suggest you, kindly go through the documentation Azure IoT Hub Documentation in case if you haven't checked earlier and let us know if you have any specific queries. We would be more than happy to help you.
You can also go through Technical Case Studies to understand how IoT Hub is used in different industries/scenarios with more details.