VBA: When conditions are met, a message box will pop up

[JennV]

Sheet1:
[TABLE="width: 500"]
<tbody>[TR]
[TD]1[/TD]
[TD]Cat[/TD]
[TD]2019-05-21[/TD]
[TD]Error... This, this, and this[/TD]
[/TR]
[TR]
[TD]2[/TD]
[TD]Dog[/TD]
[TD]2019-05-21[/TD]
[TD]Error. This, this, and this[/TD]
[/TR]
[TR]
[TD]3[/TD]
[TD]Mouse[/TD]
[TD]2019-05-25[/TD]
[TD]In order - that, that, and that[/TD]
[/TR]
[TR]
[TD]4[/TD]
[TD]Fish[/TD]
[TD]2019-05-26[/TD]
[TD]Where, when, why, and how[/TD]
[/TR]
</tbody>[/TABLE]

Sheet2:
[TABLE="width: 500"]
<tbody>[TR]
[TD]5[/TD]
[TD]2019-05-22[/TD]
[TD]Dog[/TD]
[TD]...[/TD]
[/TR]
[TR]
[TD]6[/TD]
[TD]2019-05-22[/TD]
[TD]Fish[/TD]
[TD]...[/TD]
[/TR]
[TR]
[TD]7[/TD]
[TD]2019-05-22[/TD]
[TD]Mouse[/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]

Sheet1 is my database while Sheet2 is where the user inputs data. Since there is Mouse and in the comments, it mentions 'In order', is there a way to generate a message pop up when the user tries to input comments for Mouse on Sheet2: "Note: Mouse has been previously input with 'In order'." but still allows the user to continue inputting their comments after closing that pop up? On the contrary, if Mouse had been previously input and the comments didn't mention 'In order', the pop up won't show up.

I know how to generate a userform in VBA but I'm still a beginner. I'm not sure if what I'm trying to do is possible...

Any help or guidance will be much appreciate, thank you in advance!