for converting from MBOX to PST, I would like to suggest a blog that will help you from scratch with manual as well as an alternative way. You don't need any technical knowledge for executing this. GUI of this tool is user-friendly and easy to use. It keeps the data safe & secure. You can even download the free version of this tool.
Use the great and admirable tool called Softaken MBOX to PST Converter software to convert all the MBOX data into single or separate PST. The tool is compatible with all MS Outlook editions 2019, 2016, 2013, 2010, 2007, etc. and supportive of all Windows versions such as 10, 8.1,8, 7, XP, etc. you can download demo version which converts few items from each folder.
You can move MBOX data into PST format using the manual method. Though in case if you have multiple MBOX files, then you should check any third-party proficient tools such as Stellar Converter for MBOX. It supports conversion for 17 MBOX based Email Clients and can convert MBOX file into multiple formats and provide me an ability to export the MBOX file to Office 365.