You are likely hearing the ads on TV by a few insurance companies talking about putting all of your insurance with them: homeowner, auto, etc... If you are not familiar with this method, you might want to check into it.
The word "combining" may be a little misleading. You still have an auto-specific policy and a homeowner-specific just as you have now. What is different is that both policies are written by the same company and, though you will have two different policy numbers, you typically will also have an account number that will include all the policies in your name with that company and that account number will be the prevalent identification for you with the company, rather than your policy specific numbers. The reason people "combine" all their policies under one insurance company roof is that, historically, they get better rates.
"Better rates" means a discount, of sorts, charging a lower premium for each policy than if they were stand-alones. How much of a saving will vary and you will have to compare. Better rates are not just the only benefit for having all your policies with the same company. It is sort of like centralizing your insurance - one stop shop, one agent or sales customer service to deal with. It is also possible to obtain an umbrella policy - if your company offers this coverage. If you are not familiar with the umbrella policy, it is a liability coverage that, as its name suggest, covers the underlying policies (homeowner and auto for the higher amount - payable after the exposed underlying policy's (i.e., homeowner or auto) liability coverage is exhausted and there is still exposure. Umbrella policies, typically, are for a million dollars (and more) and are a good idea if you have a lot of assets to protect. Be mindful that not all companies offer the umbrella so it will be part of your decision-making.
If you opt to move your homeowner to the auto company or vise versa - or, go with a whole new company - do not cancel your existing policy/policies that is/are to be replaced until the effective date of the new policy or policies. Very important. You do not want even 1 hour of no coverage. Most cancellations (by you or by the company) take effect on one minute after midnight on the date of cancellation. Your new policy typically takes effect one minute after midnight on the date the policy is to go into force. Write to the "old" company and request cancellation on the same date as the effective date on the new one - or the day after, to be sure! If your premium was paid up on the "old" policy and there is still time remaining in the policy period, there may be a pro rata refund coming to you.
As with any insurance purchase, DO YOUR HOMEWORK! List out what you want, what you have, what you are paying now. Find out which companies offer both auto and homeowner, an umbrella if you want it, and then comparison shop - not just for rates but for quality of coverage and quality of company. As with anything, you get what you pay for.
