现代英语，in case 多用于陈述语气，表示真实条件，等于 if 的用法，从句使用一般现在时代替一般将来时，用一般过去时代替过去将来时，直接用 if  代入即可：

Mr Wood, I am here just in case anything out of the ordinary happens.

Mr Wood, I am here just if anything out of the ordinary happens.

如果使用情态动词，用 should, 或 may/might 均可。但是，现代英语趋向简练，使用简单的陈述语气，成为主流。

这里有足够的例句，可以证明：

You hang around here in case he comes, and I'll go on ahead.
你在这附近等着以防万一他来了，我继续往前走。
《牛津词典》
Take some spare clothes in case you get wet.
多带几件衣服，以备身上弄湿了好穿。
《牛津词典》
I'll stay around in case you need me.
我就待在这儿，也许你用得着我。
《牛津词典》
You'd better take the keys in case I'm out.
你最好带上钥匙以防我不在家。
《牛津词典》
In case I forget, please remind me of my promise.
假如我忘记了，请提醒一下我的诺言。
《汉英大词典》
Don't forget to take your umbrella in case it rains.
别忘了带伞，下雨好用。
《汉英大词典》
In case you give me leave, I will start at once.
如果你许可，我立即就动身。
《汉英大词典》
In case you think I was incautious, take a look at the map.
如果你认为我不够仔细，就自己看看地图。
《柯林斯高阶英汉双解学习词典》
They are afraid to contact the social services in case they are labelled a problem family
由于害怕被贴上“问题家庭”的标签，他们不敢联系社会福利机构。
《柯林斯高阶英汉双解学习词典》
Never walk behind a horse in case it kicks out ( at you).
千万不要走在马后，它会踢你的。
《汉英大词典》
Leave your key with a neighbour in case you lock yourself out one day.
给邻居留把钥匙，以防有朝一日把自己反锁在外面。
《柯林斯高阶英汉双解学习词典》
The authorities have urged people to stock up on fuel in case hostilities break out.
当局已敦促人们储存燃料，以防战事爆发。
《柯林斯高阶英汉双解学习词典