First consider the basic case of what you are asking: you expect to have a future obligation to pay interest, and you are concerned that the rate when you pay it, will be higher than the rate today. In the simplest case, you could theoretically hedge that risk by buying an asset which pays the market interest rate. As the interest rate rises, increasing your costs, your return on this asset would also increase. This would minimize your exposure to interest rate fluctuations.
There are of course two problems with this simplified solution:
(1) The reason you expect to pay interest, is because you need/want to take on debt to purchase your house. To fully offset this risk by putting all your money in an asset which bears the market interest rate, would effectively be the same as just buying your house in cash.
(2) The timing of the future outflow is a bit unique: you will be locking in a rate, in 5 years, which will determine the payments for the 5 years after that. So unless you own this interest-paying asset for that whole future duration, you won't immediately benefit. You also won't need / want to buy that asset today, because the rates from today to 2022 are largely irrelevant to you - you want something that directly goes against the prevailing mortgage interest rate in 2022 precisely.
So in your specific case, you could in theory consider the following solution: You could short a coupon bond, likely one with a 10 year maturity date from today. As interest rates rise, the value of the coupon bond [for it's remaining life of 5 years], which has an implied interest rate set today, will drop. Because you will have shorted an asset dropping in value, you will have a gain. You could then close your short position when you buy your house in 5 years. In theory, your gain at that moment in time, would equal the present value of the rate differential between today's low mortgage rates and tomorrow's high interest rates.
There are different ways mechanically to achieve what I mention above (such as buying forward derivative contracts based on interest rates, etc.), but all methods will have a few important caveats:
(1) These will not be perfect hedges against your mortgage rates, unless the product directly relates to mortgage rates. General interest rates will only be a proxy for mortgage rates.
(2) There is additional risk in taking this type of position. Taking a short position / trading on a margin requires you to make ongoing payments to the broker in the event that your position loses money. Theoretically those losses would be offset by inherent gains in the future, if mortgage rates stay low / go lower, but that offset isn't in your plan for 5 years.
(3) 5 years may be too long of a timeline for you to accurately time the maturity of your 'hedge' position. If you end up moving in 7 years, then changes in rates between 2022-2024 might mean you lose on both your 'hedge' position and your mortgage rates.
(4) Taking on a position like this will tie up your capital - either because you are directly buying an asset you believe will offset growing interest rates, or because you are taking on a margin account for a short position (preventing you from using a margin account for other investments, to the extent you 'max out' your margin limit).
I doubt any of these solutions will be desirable to an individual looking to mitigate interest rate risk, because of the additional risks it creates, but it may help you see this idea in another light.