You will need to create a Java Bean and add it to your form. For details on how to communicate with any device, you should contact the hardware vendor in order to get the protocol and command information. Often they will also be able to provide example code for developers. In your case, you would have to enhance any example code to work as a Java Bean.
Information about creating Java Beans can be found in the Form Builder Help and many of the examples that can be found around the Internet. Here are just a few.
I ask if there is a javabean created to get data from a serial port
Or in the webutil if there is a function to do this job
Or if i can use mscomm
WebUtl would only get you part of the way there. It does not include any code that directly does serial communication. You need to write your own bean because the code needed will be unique to the device you are using.
Note that you should ignore examples that use javax.com as it is no longer supported. Consider something like jSerialComm or jRxTx or others like them.